E. V. Nikolaeva

Nanoscale backswitched domain patterning in lithium niobate

We demonstrate a promising method of nanoscale domain engineering, which allows us to fabricate regular nanoscale domain patterns consisting of strictly oriented arrays of nanodomains (diameter down to 30 nm and density up to 100 μm−2) in lithium niobate. We produce submicron domain patterns through multiplication of the domain spatial frequency as compared with the electrode one. The fabrication techniques are based on controlled backswitched poling.

Formation and evolution of charged domain walls in congruent lithium niobate

We present experimental evidence of the formation of stable charged domain walls (CDWs) in congruent lithium niobate during switching. CDW evolution under the action of field pulses was in situ visualized. CDW boundary motion velocity is about 60 μm/s at 20 kV/mm. Relief of CDW strongly depends on applied field. Dielectric response in the presence of CDW demonstrates the pronounced frequency dependence in the range 50–150 °C. We propose the mechanism of CDW self-maintained propagation governed by self-consistent electrostatic interaction between the wall’s steps.

Regular Ferroelectric Domain Array in Lithium Niobate Crystals for Nonlinear Optic Applications

Abstract We present our experimental investigations of the domain evolution in lithium niobate. Particular attention is paid to the short-pitch and nanoscale domain patterning. We demonstrate the production of domain patterns with period down to 2.6 μ.m in 0.5-mm-thick LiNbO3wafers by backswitched poling using lithographic stripe electrodes and nanoscale domain patterns consisting of strictly oriented arrays of nanodomains (diameter down to 30 nm, density up to 100 μm−2).

Kinetic approach to fatigue phenomenon in ferroelectrics

We propose an approach to the explanation of the fatigue effect as an evolution of the switching area during cyclic switching as a result of self-organized domain kinetics due to retardation of bulk screening of the depolarization field. The formation of spatially nonuniform internal bias field during cycling (kinetic imprint effect) slows the domain kinetics in some regions leading to formation of the kinetically frozen domains. Presented fatigue and rejuvenation experimental data measured in sol-gel PbZrxTi1−xO3 thin films are in accordance with the results of computer simulation.

Polarization reversal in congruent and stoichiometric lithium tantalate

Switching kinetics has been compared in congruent (CLT) and stoichiometric (SLT) lithium tantalate by simultaneous recording of instantaneous domain patterns and switching current. A mechanism of fast domain kinetics in CLT driven by domain merging was revealed. The important information about the domain kinetics has been obtained by the statistical analysis of current noise in SLT. A model of jerky domain wall motion is proposed.

Formation of Self-Similar Surface Nano-Domain Structures in Lithium Niobate Under Highly Nonequilibrium Conditions

Formation of the nanoscale domain structure in the surface layer as a result of pulsed UV laser irradiation has been studied experimentally in congruent single crystalline lithium niobate LiNbO3. The self-assembled structures have been classified and statistically analyzed. The structure is formed by growth, turning, and branching of domain rays strictly oriented along three Y+ directions. High-resolution microscopy shows that the rays represent the chains of individual needle-like nano-domains. The results of computer simulation of the domain structure formation using experimentally revealed rules are in good agreement with the experimental ones.

Domain Shape in Congruent and Stoichiometric Lithium Tantalate

Evolution of the domain shape during switching in electric field in congruent and stoichiometric lithium tantalate single crystals has been investigated both experimentally and by computer simulation. Domain patterns were observed using optical microscope. It was shown that typical domain shape is triangular for congruent lithium tantalate and hexagonal for stoichiometric one. The domain shape changes during cyclic switching. The kinetic nature of the domain shape has been proposed. The variety of domain shapes from triangular to hexagonal through intermediate shapes has been studied by computer simulation of the isolated domain growth. We report the first evidence of formation of the ordered domain structure in stoichiometric lithium tantalate with artificial dielectric layer.

Influence of adsorbed surface layer on domain growth in the field produced by conductive tip of scanning probe microscope in lithium niobate

The results of investigation of the single domain growth in electric field applied by conductive tip of the scanning probe microscope in thin plates of lithium niobate (LiNbO3) crystals doped with MgO after various surface preparations and at various ambient conditions are presented. It has been shown that the sizes of the produced domain can exceed by several orders of magnitude the value of the tip curvature radius. The observed effect has been explained taking into account the existence of the conductive adsorbed surface layer in all experimental conditions. We have demonstrated that the domain growth decelerates with decreasing of the layer conductivity. The existence of the conductive adsorbed surface layers drastically changes the spatial distribution of electric field. In addition to strongly localized electric field, just in the vicinity of the tip there exists the field component remaining homogeneous over the distance exceeding the radius of any experimentally produced domain. The crucial role of the conductive properties of the adsorbed surface layers on the screening of the depolarization field has been revealed. Within proposed approach the domain growth is controlled by the current in the external circuit including the surface layer with low conductivity. The proposed model allows us to explain time and field dependences of the domain size for various types of surface treatment. V C 2011 American Institute of Physics. [doi:10.1063/1.3624798]

Recent achievements in domain engineering in lithium niobate and lithium tantalate

Abstract We present a survey of our recent study of the field-induced domain kinetics in single-crystalline congruent lithium niobate (LN) and lithium tantalate (LT). The proposed backswitched poling by field application to the lithographically defined metal strip electrodes allows to produce periodical micro-scale structures for nonlinear optical application and to demonstrate the first achievements in domain nano-technology.

Formation of self-organized nanodomain patterns during spontaneous backswitching in lithium niobate

Abstract We show experimentally that spontaneous decay of highly non-equilibrium domain state in ferroelectric is achieved through the formation of self-organized nanoscale domain structures. The nanodomain structures have been observed by SEM and SFM in uniaxial ferroelectric lithium niobate during spontaneous backswitching after fast removing of switching field. The regular nanoscale domain patterns consist of strictly oriented arrays of nanodomains (diameter down to 30 nm, density up to 100 μm−2). The mechanisms of self-maintaining correlated nucleation effects are discussed.